ITPEC IP April 2023 Question 75

It can be read from any direction — the three square finder patterns in its corners let a reader find the orientation of a QR code.

A QR code is a matrix-type two-dimensional code: data is stored in a grid of black and white cells, both horizontally and vertically. The position-detection patterns in three corners tell the scanner where the code is and how it is rotated, so it can be read at high speed from any angle. It also carries error-correction data, so a partly dirty or damaged code can still be read.

Answer (c)

Why not others:

• •(a) — a QR code stores numbers, alphanumeric characters, binary data and double-byte characters such as kanji and kana, not only single-byte characters
• •(b) — storing data in two directions gives it far more capacity (several thousand characters) than a one-dimensional barcode (a few dozen)
• •(d) — stacking barcode rows is how a stacked-type 2D code such as PDF417 is built; a QR code is a single matrix, not three stacked layers

Key rule: A one-dimensional barcode holds data in one direction and must be scanned across; a matrix code like QR holds data in both directions, stores much more, and reads from any angle.

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